Composite metal backfilled automotive bumpers are known. For example, U.S. Pat. No. 4,569,865 teaches a thin stainless steel outer shell which is chrome plated and then backfilled with ethylene ionomers. Such composite metal and plastic bumpers have the disadvantage that the metal shell is relatively heavy, is difficult to stamp and requires extensive tooling for the stamping. The use of a metal shell has inherent design limitations and is expensive. The extensive tooling further makes it expensive and time consuming to make changes in individual components.
Previously known bumper parts do not provide a lightweight bumper which has an exterior appearance of bright metal yet are sufficiently strong to meet normal bumper impact and strength requirements.